The goals of this Core are to contribute expertise in a variety of statistical techniques that are appropriate for group and multi-level analyses. These especially include analysis of social networks and multi-level modeling, and involve techniques that have been developed in the past decade and may therefore be unknown to many investigators. Plans for this Core include activities to consult with and train investigators in new analytic techniques, provide opportunities for discussion of these techniques, and to develop statistical techniques involving social level data that can be broadly disseminated to the field.